Method for operating a spinning station of a rotor spinning machine and rotor spinning machine

ABSTRACT

A method for operating a spinning station of a rotor spinning machine includes monitoring the yarn being and upon detection of a yarn defect, stopping the spinning station and removing the yarn defect. The method specifies a certain produced yarn length or a certain time interval of yarn production and a maximum number of yarn defects within the produced yarn length or time interval. Upon detecting and exceeding a maximum number of yarn defects within the produced yarn length or the time interval, a mechanical cleaning of the spinning rotor is carried out. Alternately, a certain minimum produced yarn length or a certain minimum time interval between two yarn defects is specified and the produced yarn length or time between detection of the yarn defects is recorded. Upon undershooting the minimum produced yarn length or minimum time interval between yarn defects, the mechanical cleaning of the spinning rotor is performed.

FIELD OF THE INVENTION

The present invention relates to a method for operating a spinning station of a rotor spinning machine, in which a yarn is produced by means of a spinning rotor and the produced yarn is monitored by means of a yarn monitoring unit, wherein, upon detection of a yarn defect by the yarn monitoring unit, the spinning station is stopped and the yarn defect is removed from the yarn, whereupon the spinning rotor is cleaned at the spinning station by means of a spinning station-specific cleaning device and the yarn is re-pieced at the spinning station. The invention also relates to a rotor spinning machine that has a plurality of adjacently arranged spinning stations, each of which includes a spinning device that has a spinning rotor for producing a yarn, a yarn monitoring unit for monitoring the produced yarn, and a spinning station-specific cleaning device for cleaning the spinning rotor, and that has at least one further cleaning device for carrying out a mechanical intensive cleaning of the spinning rotor.

BACKGROUND

Rotor spinning machines that include cleaning devices for cleaning a spinning rotor have become known in multiple embodiments from the prior art. For example, rotor spinning machines are known, in which, after an interruption of production, the thread is re-pieced by means of a displaceable maintenance unit. The displaceable maintenance unit carries out a rotor cleaning prior to the piecing. For this purpose, the displaceable maintenance unit has a cleaning device that includes a cleaning head with cleaning elements, such as scrapers. In order to clean the spinning rotor, the maintenance unit is positioned in front of the relevant spinning device, opens the spinning device, advances the cleaning head toward the spinning rotor, and cleans the spinning rotor. Such a maintenance unit that includes a cleaning device is known from DE 102 31 484 A1. Due to the fact that the maintenance unit must first be positioned in front of the spinning station, the rotor cleaning is comparatively time-consuming.

Moreover, DE 27 35 311 A1 describes carrying out the cleaning of the spinning rotor by means of a pneumatic cleaning device situated at the spinning device. For this purpose, one or multiple cleaning bore(s) is/are provided in a cover element of the spinning device, through which compressed air can be blown into the spinning rotor. The compressed air is fed by the spinning machine to the spinning device and the appropriate valves are triggered, for example, by a thread monitor as soon as the thread monitor registers a thread breakage.

With respect to rotor spinning machines, it is also known to monitor the produced yarn for yarn defects by means of a yarn monitoring unit. This is described, for example, in DE 10 2015 117 204 A1. If a yarn defect is detected by the yarn monitoring unit, the relevant spinning station is stopped in a controlled manner and the yarn defect is removed by means of a so-called clearer cut. After a controlled interruption of the production of this type, the spinning station described in DE 10 2015 117 204 A1 can automatically re-piece. A rotor cleaning is not absolutely provided in this case, although a rotor cleaning can be carried out by a blowing nozzle introduced into the rotor housing from the outside, the blowing nozzle then being provided at a displaceable maintenance unit.

Finally, from the rotor spinning machine R 70 of the applicant, it is known, in the case of a clearer cut, to clean the rotor by means of a cleaning device arranged at the spinning station, the cleaning device including at least one blowing nozzle. The spinning stations are designed as so-called autonomous spinning stations, which can automatically re-piece after an interruption of the spinning process, whether it be due to a thread breakage or due to a clearer cut. Due to the spinning station-specific cleaning device, the spinning station can re-piece very quickly and without unnecessary waiting times.

It has been shown, however, that a high occurrence of yarn defects can occur despite the rotor cleaning at the spinning station. The problem addressed by the present invention is therefore that of reducing the number of yarn defects.

SUMMARY OF THE INVENTION

The problem is solved by a method for operating a spinning station of a rotor spinning machine and a rotor spinning machine having the features described and claimed herein. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In a method for operating a spinning station of a rotor spinning machine, a yarn is produced by means of a spinning rotor and the produced yarn is monitored by means of a yarn monitoring unit. Upon detection of a yarn defect by the yarn monitoring unit, the spinning station is stopped and the yarn defect is removed from the yarn. Thereafter, the spinning rotor is cleaned at the spinning station by means of a spinning station-specific cleaning device and the yarn is re-pieced at the spinning station.

With respect to the method, it is provided that a certain produced yarn length is specified and that a maximum number of yarn defects within the certain produced yarn length is specified. The number of yarn defects is then detected at least within the produced yarn length, i.e., more precisely, during the production of the certain yarn length, and, upon exceedance of the maximum number of yarn defects within the certain produced yarn length, a mechanical intensive cleaning of the spinning rotor is carried out by means of at least one further cleaning device.

It is possible, by means of this method and the counting of the yarn defects within the certain produced yarn length and/or the time interval, to detect a high occurrence of yarn defects within a short period of time and/or within short intervals, which could be due to an insufficient rotor cleaning. As soon as this is detected, a mechanical rotor cleaning can be carried out in a targeted manner by a further cleaning device. By means of the mechanical rotor cleaning, even tenacious deposits and dirt in the rotor groove can be removed, which often cannot be removed by means of a purely pneumatic rotor cleaning.

The complicated mechanical rotor cleaning is therefore carried out only for the case in which the mechanical rotor cleaning is also actually necessary due to the high occurrence of yarn defects. Although these yarn defects can be removed by means of the clearer cuts, a new, highly time-consuming piecing operation is necessary after each clearer cut, however. In addition, numerous piecings in the yarn adversely affect the quality of the yarn and can result in non-uniformly wrapped packages with bulges. Due to the fact that a mechanical rotor cleaning is carried out when there is a high occurrence of yarn defects, the yarn quality and the package quality can therefore be improved. Moreover, due to the mechanical rotor cleaning, which is carried out at least from time to time, the tendency for thread breakages to occur is also reduced and the piecing quality is improved.

Generally, on the other hand, only the fast rotor cleaning is carried out by means of the spinning station-specific cleaning device. The rotor cleaning can therefore still be carried out quickly and downtimes at the spinning stations can be reduced as a result. The machine efficiency can be improved as a result.

Preferably, the spinning station-specific cleaning device is a pneumatic cleaning device. The rotor cleaning can therefore be carried out very quickly. It would also be conceivable, however, in principle, to provide a mechanical cleaning device as a spinning station-specific cleaning device. The mechanical cleaning device could then carry out a fast standard cleaning in each case of piecing and in the case of high occurrences of yarn defects, as described above. Similarly, the mechanical intensive cleaning could also be carried out by means of a further cleaning device, however, which could be provided either at each individual spinning station or also only one time in a displaceable maintenance unit, as described further below.

Due to the specification of a certain produced yarn length, the permissible number of yarn defects can be indicated regardless of the current application, i.e., the current fiber material and yarn type, and, therefore, quality requirements can be particularly well taken into account. Alternatively to the above-described specification of a certain produced yarn length, however, according to another embodiment of the method, a certain time interval and a maximum number of yarn defects within the time interval can also be specified. The number of yarn defects at least within the time interval is then detected and, upon exceedance of the maximum number of yarn defects within the time interval, a mechanical intensive cleaning is carried out. The specification of the number of yarn defects within a certain time interval is slightly inaccurate, since the production speed will not be taken into consideration. Nevertheless, the yarn quality and the package quality can also be improved in this way and the machine efficiency can be increased.

According to a second embodiment of the method, a certain minimum produced yarn length and/or a minimum time interval between two yarn defects are/is specified and the produced yarn length upon detection of the yarn defects and/or a point in time of the detection of the yarn defects are/is recorded. Upon undershooting the minimum produced yarn length and/or the minimum time interval between two yarn defects, a mechanical intensive cleaning of the spinning rotor is carried out by means of at least one further cleaning device.

By means of this method it is also possible to detect an occurrence of yarn defects that has increased within a short time, which could be due to insufficient rotor cleaning. In this case, as described above with respect to the first embodiment of the method, a mechanical rotor cleaning is carried out in a targeted manner by a further cleaning device, in order to remove dirt in the rotor groove. In this case as well, the mechanical rotor cleaning is carried out only for the case in which the mechanical rotor cleaning is necessary due to the high occurrence of yarn defects.

Similarly, the same advantages as described above can also be achieved with this method, i.e., an improvement of the yarn quality and the package quality, an improvement of the piecing quality, and a reduction of the rate of thread breakages in combination with simultaneously reduced downtimes and an improvement of the machine efficiency.

According to an enhanced embodiment of the method, the mechanical intensive cleaning is carried out only after the minimum produced yarn length and/or the minimum time interval between two yarn defects have/has fallen below multiple times, wherein a maximum permissible number of undershooting of the minimum produced yarn length and/or of the minimum time interval is specified. As a result, it can be ruled out that a complex mechanical rotor cleaning is carried out even when, by chance, a yarn defect has occurred two times in quick succession. For example, the mechanical intensive cleaning would be carried out only when the minimum produced yarn length and/or the minimum time interval have/has fallen below three times, since only then is a high occurrence of yarn defects to be assumed.

Preferably, the minimum produced yarn length and/or the minimum time interval as well as the maximum permissible number for the undershooting of the minimum produced yarn length and/or the minimum time interval can be specified by an operator and entered into a control unit of the rotor spinning machine, which can be either a central control unit or a workstation control system of the spinning station.

Similarly, the minimum produced yarn length and/or the time interval and the maximum number of yarn defects within the minimum produced yarn length and/or the time interval can be specified by an operator preferably also upon the first execution of the method and stored in a control unit of the rotor spinning machine, which can be either a central control unit or a workstation control system.

According to an alternative embodiment, it is also possible in both methods, however, that the minimum produced yarn length and/or the minimum time interval and the maximum number for the undershooting of the minimum produced yarn length and/or the minimum time interval or the produced yarn length and/or the time interval and the maximum number of yarn defects within the yarn length and/or the time interval can be specified by the manufacturer and fixedly programmed in the particular control unit.

A rotor spinning machine that includes a plurality of adjacently arranged spinning stations, each of which has a spinning device with a spinning rotor for producing a yarn, a yarn monitoring unit for monitoring the produced yarn, and a spinning station-specific cleaning device for cleaning the spinning rotor, includes a control unit for carrying out the above-described method. Preferably, the spinning station-specific cleaning device is a pneumatic cleaning device.

As described above with respect to both methods, the produced yarn length and/or the time interval and the maximum number of yarn defects within the produced yarn length and/or the time interval or the minimum yarn length or the minimum time interval and the maximum permissible number for the undershooting of the minimum yarn length or the minimum time interval are specified in a control unit of the rotor spinning machine, which can be a central control unit or a workstation control system of the spinning station. In the case of a clearer cut, the control unit can therefore automatically prompt the particular intended type of rotor cleaning.

According to an advantageous embodiment of the rotor spinning machine, the rotor spinning machine also includes at least one further cleaning device for carrying out a mechanical intensive cleaning of the spinning rotor. This further cleaning device can be provided at each individual spinning station and also only one time within a displaceable maintenance unit.

According to an enhanced embodiment of the invention, the yarn defects are subdivided into multiple types of yarn defects and the yarn defects and/or the produced yarn length are/is recorded separately for the multiple types upon detection of the yarn defects and/or the point in time of the detection of the yarn defects. As a result, it is possible to carry out the targeted mechanical rotor cleaning sooner for certain yarn defects, which occur frequently for certain types of soiling of the spinning rotor.

It is also advantageous when, at least for one type of yarn defect, the maximum number of this yarn defect within the certain produced yarn length and/or the minimum produced yarn length between two of these yarn defects are/is specified. For example, Moiré effects often occur when dirt has settled at one certain point in the rotor groove. Due to the separate detection of Moiré effects and the specification of the maximum permissible number or the minimum produced yarn length, this dirt can be removed in a targeted manner by means of a mechanical rotor cleaning. In the case of other yarn defects, on the other hand, a higher number of yarn defects within the produced yarn length or a greater minimum yarn length between two yarn defects or multiple undershootings of the minimum yarn length may be accepted before a complex mechanical rotor cleaning is carried out. The same applies for the specification of the maximum number of yarn defects within the certain time interval or for the specification of the minimum time interval between two of these yarn defects.

The multiple types of yarn defects can include, for example, the moiré effect and the “yarn number” defect as the defect types.

It is also advantageous when the mechanical intensive cleaning is carried out by a further cleaning device of a maintenance unit that is displaceable along multiple spinning stations of the rotor spinning machine or, with respect to the rotor spinning machine, the further cleaning device is arranged in a maintenance unit, which is displaceable along multiple spinning stations. In this case, the further cleaning device must be provided only one time in the maintenance unit, so that the rotor spinning machine can be designed to be structurally simple and cost-effective. In this case, waiting times may arise until the maintenance unit has positioned itself in front of the particular spinning station. Since this is no longer necessary for each rotor cleaning, however, but rather only in certain cases, the effects on the machine efficiency are rather low overall.

According to an alternative embodiment, it is also possible, however, that the intensive cleaning is carried out by a spinning station-specific, further cleaning device. In this case, a separate mechanical cleaning device is assigned to each of the spinning stations. Waiting times for the displaceable maintenance unit can be avoided as a result.

It is therefore also advantageous when the yarn is re-pieced by means of a spinning station-specific piecing device. The spinning stations of the rotor spinning machine in this case are designed to be autonomous and, at least after a clearer step, can carry out the rotor cleaning itself and also automatically re-piece the yarn. Waiting times for a displaceable maintenance unit, which adversely affect the efficiency of the machine, therefore do not arise.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention are described in the following exemplary embodiments, wherein:

FIG. 1 shows a schematic front view of a rotor spinning machine according to a first embodiment,

FIG. 2 shows a schematic front view of a rotor spinning machine according to a second embodiment,

FIG. 3 shows a schematic, partially cut side view of a spinning station of a rotor spinning machine according to a first embodiment,

FIG. 4 shows a schematic, partially cut side view of a spinning station of a rotor spinning machine according to a second embodiment, and

FIG. 5 shows a schematic, partially cut side view of a spinning station of a rotor spinning machine that includes a displaceable maintenance unit located in front thereof.

DETAILED DESCRIPTION

Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

In the following description of the figures, the same reference signs are used for features that are identical and/or at least comparable in each of the various figures. The individual features, their embodiment and/or mode of operation are explained in detail usually only upon the first mention thereof. If individual features are not explained in detail once more, their embodiment and/or mode of operation correspond/corresponds to the embodiment and mode of operation of the features that act in the same way or have the same name and have already been described. Moreover, for the sake of clarity, often only one or only a few of several identical components and/or features is/are labeled.

FIG. 1 shows a schematic front view of a rotor spinning machine 1 according to a first embodiment. The rotor spinning machine 1 has a plurality of adjacently arranged spinning stations 2, of which only two are labeled in the present case. The spinning stations 2 are each arranged between two frames 3 generally on two longitudinal sides of the rotor spinning machine 1. Each of the spinning stations 2 has a supply unit 4 for feeding a fiber material 22 to a spinning device 7. In the spinning device 7, a yarn 8 is spun from the fiber material 22, the yarn 8 being drawn off by a take-off device 9 and fed to a winding device 12, where it is wound onto a package 13. In the present example, the yarn also passes through a waxing unit 11. The rotor spinning machine 1 also includes a central control unit 19 for controlling the functions of the rotor spinning machine 1 and/or the spinning stations 2. Moreover, according to the present representation, each of the spinning stations 2 also includes another spinning station-specific control unit. i.e., the workstation control system 20.

In the present case, a yarn monitoring unit 10 is arranged underneath the take-off device 9 at each of the spinning stations 2. By means of the yarn monitoring unit 10, the yarn 8 can be checked for yarn defects, such as thin and thick places, Moiré effects, and other defects. If a yarn defect is detected by the yarn monitoring unit 10, the yarn monitoring unit 10 triggers a so-called clearer cut. In a clearer cut, the moving yarn is cut and the defective yarn piece already traveling on the package is unwound counter to the regular winding direction, re-cut, and drawn out. Next, the yarn defect is cut out and the yarn 8 can be re-pieced. Generally, a rotor cleaning is carried out prior to the piecing. For this purpose, the spinning stations 2 each have a spinning station-specific cleaning device 16 (see FIG. 3 ), which is not shown here.

FIG. 2 shows another embodiment of a rotor spinning machine 1, which, in contrast to the rotor spinning machine 1 from FIG. 1 , includes a maintenance unit 21, which is displaceable along the spinning stations 2. The displaceable maintenance unit 21 also has a control unit 19, which is connected to the central control unit 19 of the rotor spinning machine 1, as indicated by the dash-dotted line. Moreover, the displaceable maintenance unit 21 includes a further cleaning device 18 for carrying out a rotor cleaning. For the rest, the rotor spinning machine 1 corresponds to the rotor spinning machine from FIG. 1 and, therefore, is not explained in greater detail at this point.

FIG. 3 shows a schematic, partially cut side view of a spinning station 2 of a rotor spinning machine 1 according to a first embodiment. It is apparent that the fiber material 22 is fed to the spinning device 7 by means of the supply unit 4, which includes a feed roller 5 and an opening roller 6, and, at the spinning device 7, the fiber material 22 is fed to a spinning rotor 23. The present spinning station 2 is also designed as an autonomous spinning station 2, which can automatically carry out a spinning start-up process at least after a clearer cut. The individual working elements of the spinning station, which were described above with reference to FIG. 1 , each have a separate drive 15, and so each spinning station 2 can be operated independently of the others. For this purpose, the working elements, i.e., the feed roller 5, the opening roller 6, the spinning rotor 23, the yarn monitoring unit 10, the take-off device 9, the winding device 12, and their drives 15 are connected to the workstation control system 20 for control purposes, the workstation control system 20 being connected in turn to the central control unit 19 of the rotor spinning machine 1. The spinning station 2 also has a spinning station-specific piecing device (not shown) for automatically carrying out a piecing operation. The spinning station-specific piecing device includes at least one unit for returning the yarn end into the spinning rotor 32, for example, a blowing unit.

Each of the spinning stations 2 also includes a spinning station-specific cleaning device 16, which is pneumatic in this case, for rotor cleaning. The spinning station-specific cleaning device 16 includes a blowing nozzle 17, which is arranged, in the present case, in a cover element 14, which closes the spinning device 7 during operation. The cover element 14 is arranged to swivel at the spinning station 2 in a known way. The blowing nozzle 17 is connected to a compressed air source 25 via a compressed air line 26. A coupling 24 is also provided in the compressed air line 26 in order to enable the swiveling of the cover element 14.

As described above, as soon as a yarn defect has been detected by the yarn monitoring unit 10, a clearer cut is triggered. The yarn defect is cut out and, thereafter, the yarn 8 is re-pieced. The piecings meet the quality requirements on the yarn, in principle, and so the piecings are generally not detected as yarn defects. Nevertheless, each piecing forms a thick place in the yarn. For this reason, problems can arise when the yarn 8 contains too many piecings. On the one hand, the quality of the yarn 8 suffers. On the other hand, bulges can form on the packages 13 when a plurality of piecings have been wound onto the package 13. The number of piecings on the package 13 should therefore not be too high.

For this reason, the aim is to reduce the number of clearer cuts and, therefore, the number of piecings by means of a regular rotor cleaning. For this reason, a rotor cleaning generally also takes place by means of the spinning station-specific pneumatic cleaning device 16 after a clearer cut.

The rotor cleaning can be carried out comparatively quickly by means of the spinning station-specific cleaning device 16, since, for example, in the case of a pneumatic cleaning device 16, only one valve (not shown) of the cleaning device 16 needs to be actuated for this purpose, in order to trigger a blast. The production losses due to the spinning device 7 being stopped during the rotor cleaning can be kept low as a result. A fast standard cleaning of the spinning rotor 23 is also possible in the case of a spinning station-specific mechanical cleaning device 16. If the cleaning by the spinning station-specific cleaning device 16 is insufficient, however, or if new dirt quickly arises due to the current use, further yarn defects can quickly arise despite the rotor cleaning having been carried out. As a result, the number of clearer cuts and, thereby, also the number of piecings increases, as the result of which the quality of the yarn 8 and of the package 13 can be adversely affected.

For this reason, it is provided to carry out a mechanical intensive cleaning of the spinning rotor by means of a mechanical cleaning device 16, 18 as soon as yarn defects arise again within short intervals after the piecing. The intervals can be based on yarn length distances and on time intervals. Due to the intensive cleaning, the rotor groove is intensively cleaned and freed from any adhesions, so that accumulations of yarn defects can be avoided. If necessary, an intensive cleaning of this type can also be repeated, i.e., for example, after three consecutive clearer cuts. Preferably, the operator can specify this in the central control unit 19 or the workstation control system 20 of the relevant spinning station 2. Due to the mechanical rotor cleaning, which is carried out only in the case of a high occurrence of yarn defects, the quality of the yarn 8 and of the package 13 can be improved, on the one hand, and the production losses due to the downtimes of the spinning station 2 can nevertheless be kept low.

In order to detect an accumulation of yarn defects, according to a first embodiment of the method, a maximum permissible number of yarn defects within a certain produced yarn length can be specified. The yarn defects detected by the yarn monitoring unit are registered and counted by the workstation control system 20 or the central control unit 19. If the maximum permissible number of yarn defects within the certain yarn length is exceeded, the mechanical intensive cleaning of the spinning rotor 23 is triggered by the control unit 19 or the workstation control system 20. Instead of the certain produced yarn length, a certain time interval can also be specified, within which only a certain number of yarn defects is permitted to arise.

Alternatively, it is also possible to specify a certain minimum produced yarn length and/or a certain minimum time interval between two yarn defects. The yarn defects detected by means of the yarn monitoring unit are registered by the workstation control system 20 or the central control unit 19 and, additionally, the produced yarn length upon detection of the yarn defects and/or the point in time of the detection of the yarn defects are/is also recorded. By means of the workstation control system 20 or the central control unit 19, the actually produced yarn length or the actual time interval between two yarn defects are compared with the predefined minimum yarn length and the predefined minimum time interval, respectively. If the predefined minimum yarn length and/or the predefined minimum time interval are/is fallen below, the mechanical intensive cleaning of the spinning rotor is in turn triggered.

According to a first embodiment of the method, the mechanical intensive cleaning is carried out by a further cleaning device 18, which is also arranged at the spinning station 2. FIG. 4 shows a schematic, partially cut side view of such a spinning station 2 that includes a spinning station-specific, further cleaning device 18. The further cleaning device 18 in the present example is arranged at the cover element 14, more precisely in an extension of the third element. The further cleaning device 18 can be designed, for example, as an extendable scraper, as shown in FIG. 4 .

Alternatively, a brush or another mechanical cleaning element would also be conceivable. It is also not absolutely necessary that the further mechanical cleaning device 18 is arranged at the cover element 14. It would also be possible to arrange the further cleaning device at the spinning station 2 so as to be movable and advanceable toward the spinning rotor 23. In this case, the cover element 14 would have to be first swiveled away, in order to advance the further cleaning device 18 toward the spinning rotor 23.

Moreover, it would also be conceivable to arrange only a single mechanical spinning station-specific cleaning device 16 at the spinning station, which carries out a standard cleaning in each case of piecing and also carries out a mechanical intensive cleaning as described above when there is a high accumulation of yarn defects.

According to another embodiment of the method, the mechanical intensive cleaning is carried out by a further cleaning device 18, which is arranged in a maintenance unit 21, which is displaceable along the spinning stations 2 of the rotor spinning machine 1. The configuration of a rotor spinning machine 1 of this type is shown in FIG. 2 .

FIG. 5 shows a schematic, partially cut side view of a spinning station 2 of such a rotor spinning machine 1 that includes a displaceable maintenance unit 21 located in front thereof. In the present example, the cover element 14 of the spinning device 7 has already been swiveled opened in order to enable the mechanical rotor cleaning. The swiveling of the cover element 14 can be carried out by the maintenance unit 21 and also by the spinning station 2 itself. The further cleaning device 18 in the present case is designed as a cleaning head that is advanceable toward the spinning rotor 23, the cleaning head also being provided with extendable scrapers. In the representation shown, the cleaning device 18 has already been advanced toward the spinning rotor 23 and the scrapers have already been extended.

In order to achieve optimal production while simultaneously ensuring a good yarn and package quality, it is advantageous when the parameters that define an accumulation of yarn defects can be specified in the control unit of the rotor spinning machine 19 or, if necessary, also in the workstation control system 20 individually for each spinning station 2. As described above, the parameters include the certain produced yarn length and/or the duration of the time interval and the maximum number of yarn defects or the minimum produced yarn length and/or the minimum time interval between two yarn defects and, if necessary, the permissible number of undershootings of the minimum produced yarn length and/or of the minimum interval. Preferably, this can be specified by the user him/herself, although it is possible for the manufacturer to fixedly program this into the appropriate control unit 19. Particularly advantageously, these parameters are specified separately for various types of yarn defects. This also makes it possible, for example, to carry out a time-intensive mechanical rotor cleaning only for the case in which the same yarn defect frequently arises.

The present invention is not limited to the represented and described exemplary embodiments. Modifications within the scope of the claims are also possible, as is any combination of the features, even if they are represented and described in different exemplary embodiments.

LIST OF REFERENCE SKINS

-   1 rotor spinning machine -   2 spinning station -   3 frame -   4 supply unit -   5 feed roller -   6 opening roller -   7 spinning device -   8 yarn -   9 take-off device -   10 yarn monitoring unit -   11 waxing unit -   12 winding device -   13 package -   14 cover element -   15 drive -   16 spinning station-specific cleaning device -   17 blowing nozzle -   18 further cleaning device -   19 control unit -   20 workstation control system -   21 maintenance unit -   22 fiber material -   23 spinning rotor -   24 coupling -   25 compressed air source -   26 compressed air line 

1-12: (canceled)
 13. A method for operating a spinning station of a rotor spinning machine that produces a yarn with a spinning rotor, the method comprising: monitoring the yarn being produced via a yarn monitoring unit; upon detection of a yarn defect by the yarn monitoring unit, stopping the spinning station and removing the yarn defect from the yarn; cleaning the spinning rotor with a spinning station-specific first cleaning device and then re-piecing the yarn at the spinning station; specifying a certain produced yarn length or a certain time interval of yarn production; specifying a maximum number of yarn defects within the produced yarn length or the time interval; detecting the number of yarn defects within the produced yarn length or the time interval; and upon exceeding a specified maximum number of yarn defects within the produced yarn length or the time interval, carrying out a mechanical intensive cleaning of the spinning rotor.
 14. The method of claim 13, wherein the yarn defects are subdivided into multiple types of yarn defects and the number of the yarn defects within the produced yarn length or the time interval are recorded separately for the multiple types of yarn defects.
 15. The method of claim 14, wherein the maximum number of yarn defects within the produced yarn length or the time interval is separately specified for the multiple types of yarn defects.
 16. The method of claim 13, wherein the yarn defect is a Moiré effect.
 17. The method of claim 13, wherein the mechanical intensive cleaning of the spinning rotor is carried out by a second cleaning device that is different from the first cleaning device.
 18. The method of claim 13, wherein the second cleaning device is configured on a maintenance unit that travels along multiple spinning stations of the rotor spinning machine.
 19. The method of claim 13, wherein the second cleaning device a spinning station-specific cleaning device.
 20. The method of claim 13, wherein the yarn is re-pieced by a spinning station-specific piecing device.
 21. A method for operating a spinning station of a rotor spinning machine, comprising, wherein a yarn is produced at the spinning station with a spinning rotor, the method comprising: monitoring the yarn produced at the spinning station with a yarn monitoring unit; wherein, upon detection of a yarn defect in the yarn by the yarn monitoring unit, stopping the spinning station and removing the yarn defect from the yarn; cleaning the spinning rotor with a spinning station-specific cleaning device and then re-piecing the yarn at the spinning station; specifying a certain minimum produced yarn length or a certain minimum time interval between two yarn defects; recording the produced yarn length or time between detection of the yarn defects; and upon undershooting the minimum produced yarn length or minimum time interval between two yarn defects, carrying out a mechanical intensive cleaning of the spinning rotor.
 22. The method of claim 21, wherein the mechanical intensive cleaning is carried out only after the minimum produced yarn length or the minimum time interval between two yarn defects has not been met a specified multiple number of times.
 23. The method of claim 21, wherein the yarn defects are subdivided into multiple types of yarn defects and the number of the yarn defects within the minimum produced yarn length or the minimum time interval between two yarn defects is recorded separately for the multiple types of yarn defects.
 24. The method of claim 23, wherein the minimum produced yarn length or the minimum time interval between two yarn defects is separately specified for the multiple types of yarn defects.
 25. The method of claim 21, wherein the yarn defect is a Moiré effect.
 26. The method of claim 21, wherein the mechanical intensive cleaning of the spinning rotor is carried out by a second cleaning device that is different from the first cleaning device.
 27. The method of claim 21, wherein the second cleaning device is configured on a maintenance unit that travels along multiple spinning stations of the rotor spinning machine.
 28. The method of claim 21, wherein the second cleaning device a spinning station-specific cleaning device.
 29. The method of claim 21, wherein the yarn is re-pieced by a spinning station-specific piecing device.
 30. A rotor spinning machine, comprising: a plurality of adjacently arranged spinning stations; each spinning station comprising: a spinning rotor for producing a yarn; a yarn monitoring unit for monitoring the produced yarn; a spinning station-specific cleaning device for cleaning the spinning rotor; and a control unit configured to control performance of the following: monitoring the yarn being produced via the yarn monitoring unit; upon detection of a yarn defect by the yarn monitoring unit, stopping the spinning station and removing the yarn defect from the yarn; cleaning the spinning rotor with the spinning station-specific cleaning device and then re-piecing the yarn at the spinning station; specifying a certain produced yarn length or a certain time interval of yarn production; specifying a maximum number of yarn defects within the produced yarn length or the time interval; detecting the number of yarn defects within the produced yarn length or the time interval with the yarn monitoring unit; and upon exceeding a specified maximum number of yarn defects within the produced yarn length or the time interval, carrying out a mechanical intensive cleaning of the spinning rotor with a further cleaning device.
 31. A rotor spinning machine, comprising: a plurality of adjacently arranged spinning stations; each spinning station comprising: a spinning rotor for producing a yarn; a yarn monitoring unit for monitoring the produced yarn; a spinning station-specific cleaning device for cleaning the spinning rotor; and a control unit configured to control performance of the following: monitoring the yarn being produced via the yarn monitoring unit; upon detection of a yarn defect by the yarn monitoring unit, stopping the spinning station and removing the yarn defect from the yarn; cleaning the spinning rotor with the spinning station-specific cleaning device and then re-piecing the yarn at the spinning station; specifying a certain minimum produced yarn length or a certain minimum time interval between two yarn defects; recording the produced yarn length or time between detection of the yarn defects; and upon undershooting the minimum produced yarn length or minimum time interval between two yarn defects, carrying out a mechanical intensive cleaning of the spinning rotor with a further cleaning device. 